The invention relates to a sealing roller, particularly for a device for producing a tampon for feminine hygiene as well as a method for producing a tampon.
Friese, U.S. Pat. No. 4,816,100 discloses a method and a device for producing a tampon for the feminine hygiene. The method includes sectioning a fluid permeable and at least partially thermoplastic material and heat sealing it onto an absorbent nonwoven fiber material or fleece web. Individual sections of the absorbent are severed from the fleece web supply and are wound onto themselves to form a tampon blank having a withdrawal cord. Thereby the fluid permeable cover material is positioned on the circumference of the tampon blank and surrounds it essentially completely. Finally, the tampon blank is pressed radially into the final shape of the tampon. Friese also employs a sealing roller to heat sealing the cover material onto the fleece web or the fleece web section. The sealing roller of Friese comprises heatable sealing elements that are spaced apart around the circumference of the sealing roller. Insulating means are arranged between these sealing elements. Thus, the sealing roller sealing elements and insulating elements alternate about the surface of the sealing roller in the direction of rotation.
Wilkes et al., U.S. Pat. No. 5,634,914, discloses multilimbed regenerated cellulose fibers which patentee claims provide high absorbency and a cotton-like handle. These tampons are described as having good stability and absorbency. Longitudinally-expanding tampons having these fibers are described as having less expansion than conventional longitudinally-expanding tampons.
Finally, Nguyen et al., WO97/23185 discloses tampons that can expand in the presence of high humidity after insertion into a user""s body to prevent early bypass leakage from occurring. This tampon is a substantially cylindrical mass of compressed fibers enclosed within a fluid-permeable cover. The tampon has a stability of at least about 15 N, and is capable of radially expanding upon exposure to a humid environment. The radius increases by at least about 10% after 15 minutes to 90% relative humidity at 40xc2x0 C. Particularly useful in this tampon are multilimbed fibes such as those in Wilkes et al. These fibers are relatively stiff to help the early expansion of the tampons.
Unfortunately processing these fibers causes difficulty, especially when a fibrous web having stiff fibers, such as the multilimbed fibers of Wilkes, are exposed to unexpected or undesired delays during manufacture. Such delays can allow previously calendered or compressed fibrous webs to bloom or expand, possibly due to humidity, as described in Nguyen et al. This expansion can cause jams or other undesirable process interruption.
Therefore, what is needed is a device and process to produce a high-quality tampon that secures a sufficient calendering of the fibrous fleece web for fibers that are otherwise hard to maintain in a compressed condition at a low cost.
An apparatus for thermally bonding a cover material onto an absorbent, fibrous web has a substantially cylindrical, rotatable sealing roller and a rotatable anvil roller disposed adjacent the sealing roller to provide a nip therebetween. The cover material and fibrous web can be sealed and calendered in the nip of this apparatus. The sealing roller includes a sealing element and an ironing element, and both of these elements have thermally conductive material and a leading and a trailing end in the direction of rotation. The sealing roller has at least one pair of sealing and ironing elements positioned sequentially on the circumferential surface of the sealing roller in the direction of rotation. At least one end of the ironing element is thermally insulated from an adjacent end of an adjacent sealing element.
The process for producing a tampon includes the following steps: a) applying a cover sheet to a fibrous web; b) passing the fibrous web and cover sheet combination through the nip of a sealing roller and an anvil roller; c) applying heat to a first portion of the combination at a first temperature range sufficient to bond the cover sheet to the absorbent web; and d) applying heat to a second portion of the combination at a second temperature range insufficient to bond the cover sheet to the absorbent web and sufficient to calender the fibrous web. The sealing roller provides heat at both the first and second temperature ranges to the cover sheet and fibrous web combination.
Again, it is an object of the invention to provide a device and a process to produce a high-quality tampon that secures a sufficient calendering of the fibrous fleece web for fibers that are otherwise hard to maintain in a compressed condition at a low cost device for producing a high-quality tampon which secures a sufficient calendering of the fleece web for fibers which are hard to calender at low cost. This object is solved by the apparatus including the sealing roller and the process of the present invention.